JP2007020083A - Image reader, image forming device and conveyance control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader, an image forming device and a conveyance control method in which vibration can be reduced when accelerating and decelerating an object to be conveyed. <P>SOLUTION: The image reader for reading an image of a medium on which a relevant image is recorded comprises: a holding means (fixing plate 8) for holding the medium; an image reading means (optical unit 1) for reading the recorded image; a conveyance means (linear motor 7) for conveying the holding means and/or the image reading means; a detection means (rotary encoder 51) for detecting the conveying state of the conveyance means; and a conveyance control means (conveyance controller 100) for changing, in an S shape, a speed pattern of the conveyance means in the case of acceleration to a predetermined speed and/or in the case of deceleration from a predetermined speed based on the conveying state detected by the detection means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus, an image recording apparatus, and a conveyance control method.

  Conventionally, radiation images represented by X-ray images have been widely used for diagnosis. As a method for obtaining this radiation image, a phosphor layer called an intensifying screen is irradiated with radiation transmitted through a subject, and visible light emitted from the phosphor layer is irradiated onto a silver halide photographic material. A so-called radiographic method in which a visible image is obtained by subjecting this photosensitive material to development processing has been proposed and put into practical use.

  In recent years, instead of the radiographic method described above, the irradiated radiation energy is stored and recorded, and when excited light is irradiated, the stored and recorded photostimulative light emission is performed according to the recorded radiation energy. A radiation image recording / reproducing system using a “body” has been proposed.

  In this radiographic image recording / reproducing system, a radiographic image reading apparatus is used which creates a radiographic image by converting the radiation energy stored and recorded in the stimulable phosphor into an electrical signal. The radiation image reader irradiates the stimulable phosphor with radiation that has passed through the subject, thereby storing and recording radiation energy corresponding to the radiation transmission density of each part of the subject in the stimulable phosphor, and then exciting the radiation. Radiation energy is stimulated to emit light, and the intensity of the stimulated emission light is converted into an electrical signal using a photoelectric conversion element. The electrical signal is reproduced as a visible image via an image forming apparatus that forms an image on an image recording material such as a photosensitive material or an image display device such as a CRT.

  According to the radiation image recording / reproducing method, a scanning laser beam is scanned in the main scanning direction on the imaging panel on which the photostimulable phosphor layer is formed at the time of image reading, in the sub-scanning direction perpendicular to the main scanning direction. The photostimulable phosphor sheet is generally conveyed at a constant speed. In addition, a shaft type linear motor is used for conveying the photostimulable phosphor sheet, and high-precision conveyance and reduction in image unevenness are achieved.

  Here, as shown in FIG. 8A, the photostimulable phosphor sheet is transported at a constant acceleration to a predetermined image reading speed V ′ at the image reading speed V ′. Generally, at least in the image reading section from P11 to P12, an image is read by being conveyed at a constant speed, and after reading the image, it is decelerated at a constant acceleration and stopped. Conventionally, there has been proposed a radiation image reading apparatus capable of keeping the conveyance speed in the image reading section constant.

On the other hand, a technique has been proposed in which the rotational speed of a paper feed roller is gradually accelerated from a stopped state and then accelerated to a target paper supply speed during conveyance of the paper in the paper feeding device of the image forming apparatus (for example, a patent) Reference 2).
JP 2003-344964 A JP 2003-192156 A

  The radiographic image reading apparatus described above is often provided with an anti-vibration member as shown in FIG. 8 (b), and an image reading unit that reads the radiographic image through the anti-vibration member is arranged, so that the external It is intended to reduce vibration from the.

  However, in this radiographic image reading apparatus, when the photostimulable phosphor sheet is accelerated or decelerated at a constant acceleration, the image reading apparatus or the base arranged via the vibration isolating member due to the inertial force generated by the acceleration / deceleration Vibrates, the read image becomes uneven, and a high-quality image cannot be obtained. Further, when the rigidity of the object to be conveyed is low, the object to be conveyed vibrates due to the inertial force generated by the acceleration / deceleration as described above, and thus there is a problem that the read image is uneven and a high-quality image cannot be obtained. .

  In this case, it is conceivable to reduce the influence on the read image by providing a stable section until the vibration generated by the acceleration / deceleration is reduced on the conveyance path. However, the apparatus becomes larger and the vibration is reduced. It is necessary to wait until the time. Moreover, in the radiographic image reading apparatus described in Patent Document 1, no consideration is given to the acceleration / deceleration of the conveyance target, and the above-described problem cannot be solved. Furthermore, the technique disclosed in Patent Document 2 does not consider the deceleration, and cannot be applied to the radiation image reading apparatus or the like using a shaft-type linear motor as a conveying unit.

  An object of the present invention is to provide an image reading apparatus, an image forming apparatus, and a conveyance control method capable of reducing vibration during acceleration / deceleration of an object to be conveyed.

In order to solve the above-mentioned problem, the invention described in claim 1
In the image reading apparatus that reads the image of the medium on which the image is recorded,
Holding means for holding the medium;
Image reading means for reading the recorded image;
Conveying means for conveying the holding means and / or the image reading means;
Detecting means for detecting a conveying state of the conveying means;
A transport control unit that changes a speed pattern of the transport unit to an S-shape when accelerating and / or decelerating from a predetermined speed based on the transport state detected by the detection unit; ,
It is characterized by having.

ここで、Δα＝（Ｖ₁−Ｖ₀）＊（Ｖ₁＋Ｖ₀）²／Ｌ²、Ｔ＝２Ｌ／｜Ｖ₁＋Ｖ₀｜であって、Ｖ₁は目標とする速度、Ｖ₀は搬送手段の初速度、Ｌは加速完了又は減速完了までに要する距離である。 Furthermore, the invention according to claim 2 is the invention according to claim 1,
The conveyance control means controls the speed v during acceleration and / or deceleration so as to satisfy the relationship of the following formulas (1) and (2).

Here, Δα = (V ₁ −V ₀ ) * (V ₁ + V ₀ ) ² / L ² , T = 2L / | V ₁ + V ₀ |, where V ₁ is the target speed and V ₀ is the conveyance The initial speed of the means, L, is the distance required to complete acceleration or deceleration.

Furthermore, the invention according to claim 3 is the invention according to claim 1 or 2,
The conveying means is a linear motor.

Moreover, in order to solve the said subject, invention of Claim 4 is the following.
In an image forming apparatus for recording an image on a predetermined recording medium,
Holding means for holding the recording medium;
Image forming means for recording an image on the recording medium;
Conveying means for conveying the holding means and / or the image forming means;
Detecting means for detecting a conveying state of the conveying means;
A transport control unit that changes a speed pattern of the transport unit to an S-shape when accelerating and / or decelerating from a predetermined speed based on the transport state detected by the detection unit; ,
It is characterized by having.

ここで、Δα＝（Ｖ₁−Ｖ₀）＊（Ｖ₁＋Ｖ₀）²／Ｌ²、Ｔ＝２Ｌ／｜Ｖ₁＋Ｖ₀｜であって、Ｖ₁は目標とする速度、Ｖ₀は搬送手段の初速度、Ｌは加速完了又は減速完了までに要する距離である。 Furthermore, the invention according to claim 5 is the invention according to claim 4,
The conveyance control means controls the speed v during acceleration and / or deceleration so as to satisfy the relationship of the following expressions (3) and (4).

Here, Δα = (V ₁ −V ₀ ) * (V ₁ + V ₀ ) ² / L ² , T = 2L / | V ₁ + V ₀ |, where V ₁ is the target speed and V ₀ is the conveyance The initial speed of the means, L, is the distance required to complete acceleration or deceleration.

Furthermore, the invention according to claim 6 is the invention according to claim 4 or 5,
The conveying means is a linear motor.

In order to solve the above problem, the invention according to claim 7 provides:
A transport control method in a transport apparatus, comprising: a transport unit that transports a transport object; and a detection unit that detects a transport state of the transport unit,
A transport control step of changing a speed pattern of the transport means into an S-shape when accelerating until reaching a predetermined speed and / or when decelerating from a predetermined speed based on the transport state detected by the detecting means; It is characterized by including.

ここで、Δα＝（Ｖ₁−Ｖ₀）＊（Ｖ₁＋Ｖ₀）²／Ｌ²、Ｔ＝２Ｌ／｜Ｖ₁＋Ｖ₀｜であって、Ｖ₁は目標とする速度、Ｖ₀は搬送手段の初速度、Ｌは加速完了又は減速完了までに要する距離である。 Further, the invention according to claim 8 is the invention according to claim 7,
The conveyance control process is characterized in that the speed v during acceleration and / or deceleration is controlled so as to satisfy the relationship of the following formulas (5) and (6).

Here, Δα = (V ₁ −V ₀ ) * (V ₁ + V ₀ ) ² / L ² , T = 2L / | V ₁ + V ₀ |, where V ₁ is the target speed and V ₀ is the conveyance The initial speed of the means, L, is the distance required to complete acceleration or deceleration.

Furthermore, the invention according to claim 9 is the invention according to claim 7 or 8,
The conveying means is a linear motor.

  According to the first aspect of the present invention, since it is possible to reduce the influence of inertia force generated by acceleration and / or deceleration, it is possible to reduce vibration during acceleration / deceleration of the holding unit or the image reading unit. it can. Further, since it is possible to reduce the speed unevenness (variation) of the conveyance speed during image reading, it is possible to reduce image unevenness during image reading.

  According to the second aspect of the present invention, since it is possible to reduce the influence of the inertial force generated by acceleration and / or deceleration, vibration during acceleration / deceleration of the holding unit or the image reading unit can be reduced. it can. Further, since it is possible to reduce the speed unevenness of the conveyance speed at the time of image reading, it is possible to reduce the image unevenness at the time of image reading.

  According to the third aspect of the present invention, by using a linear motor as the conveying means, it is possible to carry more stable, accurate, and better performance. Further, since it is possible to reduce the speed unevenness of the conveyance speed at the time of image reading, it is possible to reduce the image unevenness at the time of image reading.

  According to the fourth aspect of the present invention, since it is possible to reduce the influence of inertia force generated by acceleration and / or deceleration, vibration during acceleration / deceleration of the holding unit or the image forming unit can be reduced. . Further, since unevenness in the conveyance speed in image formation can be reduced, unevenness in image formation during image formation can be reduced.

  According to the fifth aspect of the present invention, since it is possible to reduce the influence of inertia force generated by acceleration and / or deceleration, vibration during acceleration / deceleration of the holding unit or the image forming unit can be reduced. . In addition, since unevenness in the conveyance speed in image formation can be reduced, image unevenness during image formation can be reduced.

  According to the invention described in claim 6, since the conveying means can be a linear motor, more stable, accurate, and good performance conveyance can be performed, and therefore, unevenness in the conveyance speed particularly in image formation can be reduced. Formed image unevenness can be reduced.

  According to the seventh aspect of the present invention, since it is possible to reduce the influence of inertia force generated by acceleration and / or deceleration, vibration during acceleration / deceleration of conveyance can be reduced.

  According to the eighth aspect of the present invention, since it is possible to reduce the influence of inertia force generated by acceleration and / or deceleration, vibration during acceleration / deceleration of conveyance can be reduced.

  According to the ninth aspect of the present invention, by using a linear motor as the conveying means, it is possible to carry more stably, accurately and with good performance.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present invention, the stimulable phosphor sheet is not rigid by itself and is difficult to handle in the apparatus, so it is rare to handle the stimulable phosphor sheet alone, and in many cases a metal plate or resin It is supported by sticking it on a support such as a plate or by housing it in a removable case called a cassette and bonding it to the inner surface of the cassette. In this way, the structure in which the photostimulable phosphor sheet is supported by the support or the cassette is referred to as a photostimulable phosphor plate in the following description. The photostimulable phosphor plate is supported by attaching the support side to a fixed plate with a rubber magnet or the like.

  The photostimulable phosphor plate absorbs the radiation transmitted through the subject at the time of photographing, and a part of the energy is accumulated as information of the radiation image in the photostimulable phosphor. The image reading apparatus according to the present invention is an apparatus for reading information on a radiographic image accumulated in such a stimulable phosphor.

  1 is a perspective view of a transport mechanism in an image reading apparatus according to an embodiment of the present invention, FIG. 2 is an XZ plan view in FIG. 1, FIG. 3 is an XY plan view in FIG. FIG. 5 is a plan view of the YZ plane in FIG. 1, and FIG.

  As shown in FIG. 1, the image reading apparatus irradiates the stimulable phosphor plate P with laser light (excitation light) from a laser light irradiation device (light source) (not shown) while scanning it. The optical unit 1 is horizontally aligned by an optical unit (reading unit) 1 that reads the image information by condensing and photoelectrically converting the photostimulated light emitted from the body plate P, and a support member 2 provided on the base 4. A guide rail 31 that guides movement in the direction is supported (fixed), and includes a linear motor (conveying means) 7 that moves the optical unit (conveying body) 1.

Further, the wire 6 and the rotary encoder unit 5 that are connected to the transport plate 33 to which the optical unit 1 is attached and move together with the optical unit 1, and the pulley 52 that transmits the movement of the optical unit 1 through the wire 6 and rotates. The rotary encoder 51 that detects the rotational speed of the pulley 52 and the transport control unit 100 that controls the transport speed of the transport plate 33 by the linear motor 7 are provided.
Hereinafter, each component will be described in detail.

  The base 4 is provided on the vibration isolating members 41 to 44 for reducing vibration. The vibration isolating members 41 to 44 are composed of a cushioning material such as a vibration isolating rubber or a gel-like member, and reduce vibration (impact) related to the base 4 from the outside due to the elasticity of the cushioning material.

  Further, the base 4 has a substantially rectangular plate shape, and the fixing plate 8 that supports the stimulable phosphor plate P is fixed on the base 4, so that the base 4 is bright. The stimulable phosphor plate P is held on the base 4 so that the laser light irradiation surface of the stimulable phosphor plate P is substantially vertical. Further, the optical unit 1 is disposed so as to face the photostimulable phosphor plate P, and the optical unit 1 is provided with a transport plate 33 attached to the lower surface so as to be movable with respect to the base 4. Thus, the optical unit 1 is movable with respect to the base 4.

  A long plate-like support member 2 extending in the horizontal direction is fixed substantially at the center of the upper surface of the base 4 so as to be substantially horizontal. A guide rail 31 for guiding the optical unit 1 in the horizontal direction is provided on the upper surface of the support member 2. The guide rail 31 is a rod-shaped member having a substantially rectangular shape in sectional view, and a guided member 32 having a substantially U-shaped sectional view guided by the guide rail 31 is engaged as shown in FIG. The guided member 32 is attached to the lower surface of the transport plate 33. As described above, the optical unit 1 is supported by the support member 2, the guide rail 31, the guided member 32, the transport plate 33 and the like so as to be movable on the base 4, and faces the photostimulable phosphor plate P. Are arranged.

  Further, on the upper surface of the base 4, a linear motor holding portion 72 for holding a magnet portion 71 constituting the linear motor 7 is provided on the side of the support member 2. The magnet part 71 is formed in a shaft shape by connecting a plurality of permanent magnets in which N poles or S poles of a permanent magnet having a circular cross section are regularly opposed to each other.

  Further, the magnet unit 71 is provided with a movable coil 73 constituting the linear motor 7. The movable coil 73 has a cylindrical coil, and the coil is covered with a box-shaped cover member. A movable coil 73 is provided on the lower surface of the transport plate 33, and the linear motor 7 is configured such that the magnet portion 71 penetrates the center of the movable coil 73.

  Further, on the upper surface of the base 4, a long plate-like holding member 9 extending in the horizontal direction in parallel with the support member 2 is fixed to the side of the linear motor holding portion 72 so as to be substantially horizontal. ing. As shown in FIG. 1, fixing members 91a and 91b having substantially L-shaped cross-sections are respectively provided at both ends in the longitudinal direction of the upper surface of the holding member 9, and both ends of the wire 6 are connected to these fixing members 91a and 91b. The rotary encoder unit 5 is coupled to the wire 6.

  The rotary encoder unit 5 is connected to a support base 53 fixed to the transport plate 33 and movable together with the transport plate 33, a rotary encoder 51 provided on the support base 53, and a rotary shaft (not shown) of the rotary encoder 51. And a pulley 52 attached to the lower surface of the support base 53.

  Thus, the wire 6 wound around the pulley 52 moves in the horizontal direction in conjunction with the movement of the optical unit 1 and the transport plate 33. Then, the rotary encoder 51 detects the position of the transport plate 33 from the pulley 52 rotated by the movement of the wire 6 and the rotary shaft of the rotary encoder 51. The detected position information is output to the transport control unit 100.

  As shown in FIG. 5, the transport control unit 100 includes a control unit 101, a storage unit 102, a position speed calculation unit 103, a difference output unit 104, a controller 105, a motor drive unit 106, and the like. The

  The control unit 101 outputs a speed command signal instructing the conveyance speed of the optical unit 1 (conveyance plate 33) by the linear motor 7 to the differential output device 104, and comprehensively controls the conveyance speed of the optical unit 1 at the time of image reading. To do. In addition, the control unit 101 sets the conveyance speed of the conveyance plate 33 to an S-shape based on an LUT (Look Up Table) 1021 stored in the storage unit 102 when the optical unit 1 is accelerated and / or decelerated. A speed command signal to be changed to is output to the difference output unit 104. Note that the control unit 101 may be configured by a digital circuit including a CPU (Central Processing Unit), a digital logic circuit, a microcomputer, or the like, or may be configured by an analog circuit. You may comprise combining.

  The storage unit 102 stores in advance an LUT 1021 that defines a conveyance speed when the optical unit 1 is accelerated and decelerated. Hereinafter, the LUT 1021 will be described.

The LUT 1021 is a table in which the relationship between the time t at the time of acceleration and / or deceleration of the transport plate 33 and the transport speed v is defined, and is configured based on values derived from the following formulas (7) and (8). Has been. Here, the acceleration fluctuation amount Δα = (V ₁ −V ₀ ) * (V ₁ + V ₀ ) ² / L ² , and the time limit T 2 L / | V ₁ + V ₀ | V ₁ is the target speed, V ₀ is the initial speed of the conveying means, and L is the distance required to complete acceleration and / or deceleration. Here, it is assumed that predetermined values are set in advance for the target speed V and the distance L, and the set values are stored in the storage unit 102 in advance. Note that any or all of the target speed V, the distance L, and the time limit T may be set in advance.

The value of the acceleration fluctuation amount Δα preferably satisfies the relationship of the following formula (9). In this case, the time limit T is more preferably set to the following formula (10). Here, Δα ₀ is an acceleration fluctuation amount considering the actual operating conditions of the image reading apparatus such as the rigidity and mass of the conveyance object conveyed by the linear motor 7, the weight of the conveyance mechanism itself, and the elastic coefficient of the vibration isolation member. It is. Thereby, since the conveyance speed of the conveyance plate 33 can be controlled based on the acceleration fluctuation amount Δα according to the characteristics of the conveyance mechanism, it is possible to further reduce the influence of the inertia force generated by acceleration and / or deceleration. It becomes. For example, when the mass of the object to be transported is 10 kg and the natural vibration frequency obtained from the mass of the structure on the vibration isolating member and the elastic coefficient of the vibration isolating member is 40 Hz, the acceleration change amount Δα ₀ is 10 m / s as a result of the experiment. ^3, and therefore, the value of the acceleration variation Δα is preferably made to be 10 m / s ³ below. Here, the acceleration change amount Δα ₀ is Δα ₀ > 0 during acceleration and Δα ₀ <0 during deceleration.

FIG. 6 is a diagram for explaining an example of the relationship between the time t and the conveyance speed v at the time of acceleration of the conveyance plate 33 defined based on the above formula. In the figure, the case where V ₀ = 0, V ₁ = 10 mm / s, and the time limit T = 2.0 sec is illustrated.
As shown in the figure, the speed pattern during acceleration draws an S shape with an acceleration time t = 1.0 as an inflection point, and the transport speed of the transport plate 33 is controlled based on this speed pattern. Will be. Although the speed pattern at the time of deceleration of the linear motor 7 is not shown in the figure, the speed pattern of FIG.

  In the LUT 1021, a conveyance speed v that embodies this speed pattern is recorded in association with the time t, and the LUT 1021 is read from the control unit 101 when the conveyance plate 33 is accelerated and decelerated, so that an S-shape is obtained. A speed command signal for instructing a continuous speed pattern is output to the differential output device 113. In this way, by changing the speed pattern at the time of acceleration and / or deceleration of the transport plate 33 into an S shape, it is possible to reduce the influence of inertia force generated by acceleration and / or deceleration.

  Note that the mode of the speed pattern recorded in the LUT 1021 is not particularly limited. For example, a basic speed pattern normalized by a predetermined function or the like may be stored as the LUT 1021, and a speed pattern optimum for the target speed may be derived based on the LUT 1021 and the target speed. In this case, since the data amount of the LUT 1021 can be reduced, the storage capacity of the storage unit 102 can be saved.

  In addition, when the conveyance speed is controlled digitally, an LUT 1021 in which the conveyance speed v is recorded every predetermined time interval may be used in order to perform the control in discrete time. The conveyance speed v at the determined time may be derived by linear interpolation or the like. In this case, it is preferable that a time interval for recording in the LUT 1021 is set so that the amount of change in acceleration in the speed pattern is a predetermined value or less. Further, since the amount of change in acceleration is reversed at t = 0.5T (T = 1.0 in the case of FIG. 6), it is preferable to generate the LUT 1021 having a section in which the amount of change in acceleration is zero.

  In the present embodiment, the control unit 101 instructs the speed pattern based on the LUT 1021 described above. However, the present invention is not limited to this, and the equations (13) to (16) calculated by the control unit 101 are calculated. The speed pattern at the time or motor position may be indicated based on the calculated value.

  The position speed calculation unit 103 derives a speed signal indicating the transport speed of the transport plate 33 based on the position signal input from the rotary encoder 51 and outputs the speed signal to the difference output unit 104. The difference output unit 104 generates a difference signal according to the difference between the speed command signal input from the control unit 101 and the speed signal input from the position speed calculation unit 103 and outputs the difference signal to the controller 105.

  The controller 105 derives a power value to be supplied to the linear motor 7 based on the difference signal input from the difference output unit 104, and outputs this power value to the motor drive unit 106 as a drive control signal. The control method by the controller 105 is not particularly limited, and for example, PID control that is classical control, H∞ control that is modern control, or the like can be used. The controller 105 may be configured by a digital circuit including a CPU, a digital logic circuit, a microcomputer, or the like, may be configured by an analog circuit, or may be configured by combining a digital circuit and an analog circuit. May be.

  The motor drive unit 106 drives the linear motor 7 by supplying drive power to the linear motor 7 based on the drive control signal input from the controller 105.

  The optical unit 1 includes a laser light irradiation device that irradiates the stimulable phosphor plate P with the laser light L1 while scanning in a direction perpendicular to the moving direction of the stimulable phosphor plate P, and a laser light irradiation device. A light guide plate 13 that guides the photostimulable luminescent light L2 excited by irradiating the photostimulable phosphor plate P with the laser light L1, and the photostimulable luminescent light L2 guided by the light guide plate 13 is condensed. And a photoelectric converter 12 that converts the photostimulable luminescent light collected by the condenser tube 11 into an electrical signal.

  In the image reading apparatus of the present invention, after the radiation energy is read by the optical unit 1, the stimulable phosphor plate P is discharged to emit the radiation energy remaining on the stimulable phosphor plate P. An erasing device (not shown) for irradiating erasing light is provided.

Next, the operation of the image reading apparatus having the above configuration will be described.
First, the photostimulable phosphor plate P is taken into the image reading apparatus and fixed to the fixing plate 8. Thereafter, the conveyance control unit 100 drives the linear motor 7 so that the conveyance plate 33 supporting the optical unit 1 is conveyed in the horizontal direction along the guide rail 31 from the predetermined conveyance start position. As a result, the optical unit 1 is transported to a position facing the laser irradiation surface of the photostimulable phosphor plate P (hereinafter referred to as a reading start position), and an image is read from a stopped state where the transport speed v = 0. The vehicle is accelerated to a predetermined target speed V. Here, the transport position of the transport plate 33 at the time of acceleration is detected by the rotary encoder 51, and this detection signal is input to the difference output unit 104 as a speed signal via the position speed calculation means 103.

  The control unit 101 changes the transport speed of the transport plate 33 to an S-shaped speed pattern based on the LUT 1021 stored in the storage unit 102 when accelerating from the stop state of the transport speed v = 0 to the target speed V. The speed command signal is output to the difference output unit 104. The difference output unit 104 outputs a difference signal to the controller 105 in accordance with the difference between the input speed command signal and the speed signal. The controller 105 derives a power value to be supplied from the motor driving unit 106 to the linear motor 7 based on the difference signal input from the difference output unit 104, and uses the power value as a drive control signal to drive the motor driving unit 106. Output to, the conveyance speed of the conveyance plate 33 conveyed by the linear motor 7 is controlled so that the S-shaped velocity pattern instructed by the control unit 101 is obtained. Here, when a linear motor having a U-phase, V-phase, and W-phase three-phase motor is used as the linear motor (conveying means) 7, the U-phase, V-phase, and W-phase are changed according to the position of the motor. May be derived based on the position signal output from the rotary encoder 51.

  FIG. 7 is a diagram showing the relationship between the position of the transport plate 33 on the guide rail 31 and the transport speed. As shown in FIG. 7, the speed pattern until the transport plate 33 reaches the target speed V is S-shaped when accelerating from the transport start position P0 to the reading start position P1. Here, the distance from P0 to P1 in which the horizontal axis indicates the position of the transport plate 33 on the guide rail 31 and the vertical axis indicates the transport speed of the transport plate 33 corresponds to the distance L described above. In the same figure, P2 indicates a reading completion position, which will be described later, and P3 indicates a conveyance stop position, which will be described later. Reading of the photostimulable phosphor plate P is performed in a section between P1 and P2.

  The optical unit 1 moved to the reading start position is moved at a constant reading speed V along the horizontal direction of the photostimulable phosphor plate P. During this time, the laser light is emitted from the laser light irradiation device to the photostimulable phosphor plate. Scanned against P. At this time, the laser beam is irradiated while scanning in a direction orthogonal to the moving direction of the optical unit 1. As a result, the excited stimulated emission light is guided by a light guide plate (not shown), collected on the condenser tube 11, and converted into an electric signal by the photoelectric converter 12.

  Next, when the optical unit 1 is transported to one end of the photostimulable phosphor plate P (hereinafter referred to as a reading completion position) and reading is completed, the transport control unit 100 decelerates the transport plate 33 from the reading speed V. Then, the transport plate 33 is stopped at a predetermined transport stop position on the guide rail 31. Even during the deceleration, the conveyance control unit 100 causes the conveyance speed of the conveyance plate 33 to be decelerated in an S-shaped speed pattern based on the LUT 1021 stored in the storage unit 102, as in the above-described acceleration. The driving power of the motor driving unit 106 is controlled. As a result, as shown in FIG. 5, when decelerating from the reading completion position P2 to the conveyance stop position P3, the speed pattern until the conveyance plate 33 is stopped is S-shaped (reverse S). Here, the distance from P2 to P3 corresponds to the distance L described above.

  Thereafter, the photostimulable phosphor plate P is irradiated with erase light by an eraser (not shown), thereby erasing the radiation image remaining on the photostimulable phosphor plate P. Then, the photostimulable phosphor plate P is conveyed outside the image reading apparatus.

  As described above, according to the present embodiment, it is possible to reduce the influence of the inertial force generated by acceleration and deceleration, and therefore vibration during acceleration / deceleration of the optical unit 1 (conveyance plate 33) can be reduced. Further, since it is possible to reduce the speed unevenness of the conveyance speed at the time of image reading, it is possible to reduce the image unevenness at the time of image reading.

  In the above-described embodiment, the optical unit 1 that reads the photostimulable phosphor plate P held on the fixed plate 8 is transported by the linear motor 7. However, the present invention is not limited thereto, and the optical unit 1 is fixed. It is good also as an aspect which reads the photostimulable phosphor plate P by conveying the fixed plate 8 by the linear motor 7. Moreover, it is good also as an aspect which conveys both the optical unit 1 and the stationary plate 8 by providing further another conveyance means (linear motor 7). .

  The detailed configuration and detailed operation of the image forming apparatus in the above embodiment can be changed as appropriate without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the embodiment of the image reading apparatus has been described. However, the present invention is not limited to this. In addition, the above-described transport mechanism of the image reading apparatus may be used as the transport mechanism of the image forming apparatus that records an image. In this case, the image forming unit and / or the holding unit that holds the storage medium may be conveyed. Thereby, the effect similar to this invention is acquired.

  Moreover, in the said embodiment, although the rotary encoder 51 was used as a position detection means, it is good also as not only using this but other position detection means, such as a linear encoder and a resolver. Further, the detection means is not particularly limited as long as it is a detection means capable of obtaining the conveyance speed of the conveyance plate 33. For example, the position detection means for detecting the position change of the conveyance plate 33 such as a laser displacement meter is used. It is good also as an aspect which derives | leads-out the conveyance speed of the conveyance board 33 by time-differentiating the value of the detection signal output from a position detection means. Moreover, it is good also as an aspect which derives | leads-out the conveyance speed of the conveyance board 33 by using the acceleration sensor which detects the acceleration of the conveyance board 33, and integrating the value of the detection signal from the said acceleration sensor.

  In the above embodiment, the speed pattern of the transport speed at the time of acceleration and deceleration of the transport plate 33 is changed to an S shape. However, the present invention is not limited to this. It is good also as an aspect which changes the speed pattern of the conveyance speed in S shape.

  Furthermore, in the above embodiment, the case where a shaft type linear motor is used as the conveying means has been described. However, the present invention is not limited to this. A rotary motor, a DC motor, or the like that linearly conveys may be used.

FIG. 6 is a perspective view of a transport mechanism in the image reading apparatus. FIG. 2 is an XY plan view of the transport mechanism in FIG. 1. FIG. 2 is an XY plan view of the transport mechanism in FIG. 1. It is a YZ top view in the conveyance mechanism of FIG. 3 is a block diagram illustrating a conveyance control unit of the image reading apparatus. FIG. It is a figure for demonstrating the relationship field of the time at the time of acceleration, and a conveyance speed. It is the figure which showed the relationship between the position of a moving board, and a conveyance speed. (A) It is the figure which showed the relationship between the position of a conveyance target object, and the conveyance speed in the past. (B) It is the figure which showed the structure of the image reading apparatus typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical unit 11 Condenser tube 12 Photoelectric converter 13 Light guide plate 2 Support member 31 Guide rail 32 Guided member 33 Conveyance plate 34 Motor drive part 4 Base 41 Vibration isolation member 42 Vibration isolation member 43 Vibration isolation member 44 Vibration isolation member DESCRIPTION OF SYMBOLS 5 Rotary encoder unit 51 Rotary encoder 52 Pulley 53 Support stand 6 Wire 7 Linear motor 71 Magnet part 72 Linear motor holding part 73 Movable coil 8 Fixed plate 9 Holding member 91a Fixed member 91b Fixed member 100 Conveyance control part 101 Control part 102 Storage part 1021 LUT
103 Position speed calculation means 104 Difference output unit 105 Controller 106 Motor drive unit

Claims (9)

In the image reading apparatus that reads the image of the medium on which the image is recorded,
Holding means for holding the medium;
Image reading means for reading the recorded image;
Conveying means for conveying the holding means and / or the image reading means;
Detecting means for detecting a conveying state of the conveying means;
A transport control unit that changes a speed pattern of the transport unit to an S-shape when accelerating and / or decelerating from a predetermined speed based on the transport state detected by the detection unit; ,
An image reading apparatus comprising: 2. The image reading apparatus according to claim 1, wherein the conveyance control unit performs control so that a speed v at the time of acceleration and / or deceleration satisfies a relationship of the following formulas (1) and (2).

Here, Δα = (V ₁ −V ₀ ) * (V ₁ + V ₀ ) ² / L ² , T = 2L / | V ₁ + V ₀ |, where V ₁ is the target speed and V ₀ is the conveyance The initial speed of the means, L, is the distance required to complete acceleration or deceleration.   The image reading apparatus according to claim 1, wherein the conveying unit is a linear motor. In an image forming apparatus for recording an image on a predetermined recording medium,
Holding means for holding the recording medium;
Image forming means for recording an image on the recording medium;
Conveying means for conveying the holding means and / or the image forming means;
Detecting means for detecting a conveying state of the conveying means;
A transport control unit that changes a speed pattern of the transport unit to an S-shape when accelerating and / or decelerating from a predetermined speed based on the transport state detected by the detection unit; ,
An image forming apparatus comprising: 5. The image forming apparatus according to claim 4, wherein the conveyance control unit performs control so that a speed v at the time of acceleration and / or deceleration satisfies a relationship of the following formulas (3) and (4).

Here, Δα = (V ₁ −V ₀ ) * (V ₁ + V ₀ ) ² / L ² , T = 2L / | V ₁ + V ₀ |, where V ₁ is the target speed and V ₀ is the conveyance The initial speed of the means, L, is the distance required to complete acceleration or deceleration.   The image forming apparatus according to claim 4, wherein the conveying unit is a linear motor. A transport control method in a transport apparatus, comprising: a transport unit that transports a transport object; and a detection unit that detects a transport state of the transport unit,
A transport control step of changing a speed pattern of the transport means into an S-shape when accelerating until reaching a predetermined speed and / or when decelerating from a predetermined speed based on the transport state detected by the detecting means; A conveyance control method comprising: The conveyance control method according to claim 7, wherein the conveyance control step performs control so that a speed v at the time of acceleration and / or deceleration satisfies the relationship of the following formulas (5) and (6).

Here, Δα = (V ₁ −V ₀ ) * (V ₁ + V ₀ ) ² / L ² , T = 2L / | V ₁ + V ₀ |, where V ₁ is the target speed and V ₀ is the conveyance The initial speed of the means, L, is the distance required to complete acceleration or deceleration.   The transport control method according to claim 7, wherein the transport unit is a linear motor.

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